Egg carton



May 5, 1970 D. w. DONOVAN 3,510,049

EGG CARTON Filed NOV. 21, 1968 I40 I2 14b FIG, 3

INVENTOR. DONALD W DONOVAN Attorney United States Patent f 3,510,049 EGG CARTON Donald W. Donovan, Glastonbury, Conn., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware Continuation-impart of application Ser. No. 500,515,

Oct. 22, 1965. This application Nov. 21., 1968, Ser.

Int. Cl. 365d 5/66, 1/00 US. Cl. 229-44 8 Claims ABSTRACT OF THE DISCLOSURE A display carton for eggs and like objects comprising a foamed plastic lower section having a plurality of article receiving pockets formed therein, in combination with a cover section of unfoamed, transparent, rigid plastic, hingedly connected along a portion of the foamed lower section which has a density greater than that of the remainder of the lower section.

This application is a continuation in part of copending application Ser. No. 500,515, filed Oct. 22, 1965, now US. Pat. No. 3,424,363.

The present invention relates to packages and more specifically to packages having a plurality of article receiving compartments or sections for items such as eggs, vegetables, fruit and the like to a method for making same.

It is an object of the present invention to provide a novel and relatively high strength compartmentalized package for small fragile items.

Another object of the present invention is to provide a multicompartmented package which is simple and readily fabricated.

Another object of the present invention is to provide a multicompartmented package having a transparent top.

Another object of the present invention is to provide a multicompartmented package having a transparent top which is hingedly connected to a foamed plastic bottom.

An additional object of the present invention is to provide a display carton for eggs and like objects which provides the optimum combination of structural and article cushioning characteristics in the carton.

Another object of the present invention is to provide a display carton for eggs and the like having a cover hingedly connected to a bottom of foamed plastic, wherein the density of the foam is such as to avoid structurally weakening the carton in the region of the hinged connection.

A further object of this invention is to provide method and means by which to attain the preceding objects.

Other objects of this invention will in part be obvious and will in part appear hereinafter.

These and other objects are attained by a display carton for eggs and like objects comprising a lower section of foamed plastic, the lower section having a plurality of article receiving pockets formed therein, a cover section of unfoamed, transparent, rigid plastic hingedly connected to the lower section, locking means associated with the lower and cover sections for temporarily locking the carton, the lower section having a density in the area of the hinged connection which is greater than the density of the remainder of the lower section.

The following drawings are provided for the purpose of illustrating various embodiments of the present invention.

FIG. 1 is a perspective view of an egg carton having a multicompartmented foamed bottom section and a top transparent plastic section.

FIG. 2 is a side view of an egg carton having a multicompartmented foam bottom and a top transparent plastic 3,510,049 Patented May 5, 1970 section sealed to the bottom section partly around their respective contacting edges.

FIG. 3 is a side view illustrating a type of hinge connection.

Referring to the drawings and more specifically to FIG. 1, there is schematically shown an egg carton having a foam plastic bottom section 10 and an entirely transparent rigid plastic top section 12. The bottom section 10 is composed of foamed plastic which has been molded to provide article receiving pockets or depressions shaped to securely hold items such as eggs. The depressions may have lower concave inward portions, as shown, to provide enhanced cushioning of the enclosed articles. Bottom section 10 has a density of 10 pounds per cu. ft. The top section 12 is formed from a transparent plastic piece which permits viewing of items retained by the bottom section 10. Top section 12 has a generally flat top and planar sides integrally joined to the periphery of the top and depending outwardly therefrom.

A rather unique method of hingedly securing the top and bottom plastic sections together has been developed. Though the density of the foam of the bottom section is relatively low in the article holding portion of this section to provide the optimum combination of article cushioning characteristics in the package at minimum cost, the foam in the hinge area has been compressed to increase its density and therefore the strength in this area, as we l as to provide a hinge line in the foam plastic. Thus the density of the foam in the hinge area of the package is greater than that of the remainder of the bottom section. This area of reduced thickness is designated as lip portion 16a in FIG. 2.

The preferred method of joining the top and bottom sections is by means of an adhesive applied along one side of the package as shown in FIG. 2. Lip portions are provided on both sides of the top transparent section 12 and the bottom foam section 10 extending outwardly around the periphery of each. These are designated as 14a and 14b for the top section and 16a and 16b for the bottom Section. As illustrated in FIG. 2, lip portions 14a and 14b of the top section 12 abut lip portions 16a and 16b of the lower section 10 and are adhesively secured together as indicated at 20. Since the opposite side is not secured at edges 14b and 1612, then a hinge effect is attained.

An alternative type of hinge is shown in FIG. 3 wherein the top section 32 is turned over at one edge producing a rounded portion 34 which is adhered to edge 36 of bottom portion 30 by means of a heat seal. The curved portion 34 lends suflicient flexibility to permit pivoting of the rather rigid cover at this point without rupture along the seam of the container. Any suitable locking means may be utilized at the opposite edge from that where the hinge connection is located for temporarily locking edges 14b and 16b, for example, spot sealing as shown at 21, locking flaps, clips, etc.

The above description and particularly the drawings are set forth for the purposes of illustration only and not for the purpose of limitation.

Although the illustrated embodiment is one having a particular utility for eggs, the package may be formed for the storage, shipment and display of other fragile items such as fruit, vegetables and various other fragile and/or ornamental articles such as tree ornaments, toys, confections, baked goods and the like. Consequently, the package may assume a wide variety of shapes and the shape of the individual depressions may vary widely to conform to the contours of irregularly shaped items, for example, square, round, oval, cylindrical and the like. When the carton is utilized to hold eggs as for the configuration of the preferred embodiment, twelve article receiving compartments are provided with six compartments aligned on each side of the carton axis. However two rows located on each side of the carton axis of three compartments per row are also suitable.

As earlier indicated, the bottom section of the package is formed from a substantially planar foamed sheet which has been molded to produce a plurality of compartments. The type of plastic which may be used to form the bottom portion of the package may be any plastic which is capable of being manufactured in cellular form according to design parameters defined hereafter. Particularly preferred materials are plastic polymers based on styrene monomer, since foamed plastics made of these materials can be thermoformed into relatively strong and rather deep compartments for enclosing eggs and the like, as opposed to other structurally weaker foams which are limited to shallow draws during thermoforming. Generally, the thickness of the foamed section will range between about 15 mils to 300 mils.

The physical properties of the foamed plastic from which the lower section of the carton is fabricated should be selected to provide article cushioning characteristics and structural stability in the carton. More specifically, the density of the plastic of the bottom section should range between about 4 to 40 pounds per cu. ft. For densities in excess of 40 pounds per cu. ft., the resiliency of the foam is generally insufficient to adequately cushion fragile articles whereas with relatively low density foams below 4 pounds per cu. ft., the void space is excessive so as to adversely affect the structural properties of the package for an economically practical thickness, thus increasing the possibility of collapse or damage during stacking and bulk handling. A preferred density range is on the order of 6 to 15 pounds per cu. ft. At this density range the cover may be economically manufactured, readily attached and repeatedly pivoted without collapsing the foamed bottom.

Plastic foam cell size may also play a role in providing the optimum properties in the bottom section of the package. In general, the cell size of the foam should range between about 2 to 10 mils. Values outside these limits either fail to provide the desired cushioning effect in the carton or adversely affect the structural stability and appearance of the package.

The top portion of the package is formed of a fairly rigid unfoamed plastic which is at least partially and preferably entirely transparent, and which is sufliciently compatible with the plastic foamed bottom section to be scalable therewith at least at the edges thereof. A particularly preferred plastic material for the top section is biaxially oriented polystyrene which is fairly rigid and substantially transparent. When the cover is of the planar variety as set forth in the preferred embodiment, the sides thereof preferably depend from the top at an angle with a vertical plane through the edge of the top of between about 10 to 60 degrees, in order to provide vertical load strength in the package. The cover may, if desired, be provided with load bearing posts extending downwardly from its underside and cooperating with supports in the bottom portion. This may be especially desirable when the cover is fabricated of rather thin material. Other suitable plastics which may be used as the cover are polyethylene or polypropylene; styrene copolymers, for instance, styrene-acrylonitrile copolymers; polyacrylates, polymethacrylates; polycarbonates; polyvinyl chloride; and polyethylene terephthalates.

The plastic cover can be in the form of a flat sheet or a sheet molded to any desired shape, for instance by a thermoforming process, such as by vacuum-forming or pressure-forming. The cover is normally relatively thin, generally ranging between 1 to 50 mils and preferably to 30 mils.

Preferably, the top and bottom portions of the package are molded from substantially planar material, the bot tom portion being molded from foamed plastic sheet material while the top portion is molded from unfoamed plastic sheet material. Although it is generally desirable to employ the same type of plastic for the top and bottom portions, it is possible to select different materials having as good or better sealing characteristics.

As previously indicated, the top portion is fabricated separately from the bottom section and must thereafter be hingedly connected to the bottom. The preferred type of hinge connection is by means of an adhesive, which must be substantially inert to the lid as well as the foamed bottom to avoid any reaction therewith which might collapse the foam cell structure. Preferably the foam portion of the carton should bend during opening since this is more resilient than the stiffer cover material. An alternate manner of attachment is by means of a heat seal along the edges of the top and bottom sections of the carton, or by means of a separate sealing tape or other mechanical means. In any event, the engaging portions of the sections in the region of the hinged attachment must overlap sufficiently to provide adequate strength in the hinged area. The extent of the overlap should be at least inch and preferably between about to 1% inches. If desired, only one side of the top and bottom members need be sealed together to provide a hinge for the top and bottom members to pivot on. In the alternative both elongated sides of the carton may have hinged connections, with the opening extending along the center of the package. The container can be closed by any suitable locking means associated with the opposite side of the container from that where a hinge is located.

When the hinged connection is provided by means of a heat seal, the operation is performed at a temperature sufficient to cause fusion of the foamed-unfoamed abutting portions. In the case of biaxially oriented polystyrene and a foamed polymer material based on styrene the heat sealing operation is performed at a temperature between and 305 F., preferably between 250 and 300 F., and at a pressure between 5 and 40 pounds per square inch. The pressure depends, of course, to some extent on the temperature, with higher pressures being required where the temperature is lower and vice versa. A press can be used for example, which has electricallyheated jaws shaped to conform to the edges of the container. When the joint is made in this manner, the foam of the bottom in the hinge area of the carton need not be separately compacted initially, since this is adequately accomplished in the heat sealing operation. The jaws can be maintained at the sealing temperature by means of a thermostat, but preferably there is used an impulse heat-sealing method where the jaws are only heated for a brief period of time and then allowed to cool while pressure is still applied. A heating period of up to 5 seconds, for instance between 2 and 4- seconds, is often sufiicient; the cooling time can, for instance, be between 1 and 3 seconds.

As can be readily appreciated, the present invention provides a package which is relatively simple to fabricate and which has unique cushioning properties for protecting contained articles from damage due to shock or impact, While exhibiting structural stability characteristics. Furthermore, the package has unique adaptability to high speed production operations primarily because of the ease with which the top and bottom portions may be connected together to provide a hinged package.

The above description and particularly the drawings are set forth for purposes of illustration only. Many variations and modifications thereof will be obvious to those skilled in the art and can be made without departing from the spirit and scope of the invention.

What is caimed is:

1. A display carton for eggs and like objects compris ing a lower section entirely of foamed plastic, said lower section having a plurality of article receiving pockets formed therein, a cover section of unfoamed transparent rigid plastic hingedly connected to the lower section,

locking means associated with said lower and cover sec tions for temporarily locking said carton, said lower section having a density in the area of the hinged connection which is greater than the density of the remainder of the lower section.

2. The carton of claim 1 wherein the density of the foam in the region of the hinged connection of the cover section to the lower section is between 6 to 15 pounds per cu. ft. 1

3. The carton of claim 1 wherein the cell size of the foam is between 2 to mils.

4. The carton of claim 1 wherein the lower section is made of a foamed plastic based on styrene.

5. The carton of claim 1 wherein the cover section is attached to the lower section by means of a heat seal.

6. A display carton for eggs and like objects comprising a lower section entirely of foamed plastic having a density of between 4 to 40 pounds per cu. ft., said lower section having a plurality of upwardly opening article receiving pockets formed therein, a lip at its upper end extending outwardly around the periphery thereof, said carton further comprising a cover section of unfoamed, entirely transparent, rigid plastic, said cover being hingedly attached to the lower section by means of an adhesive along mutually adjacent edges to permit opening the carton by pivoting the cover section about the hinged attachment, said lower section having a density in the area of the hinged connection which is greater than the density of the remainder of the lower section and locking means integrally associated with the lower and cover sections along the side of each which is opposite the side where said hinged connection is located.

7. A display carton for eggs and like objects comprising a bottom section composed entirely of a foamed plastic polymer based on styrene monomer, said foamed plastic having a density of between 6 to pounds per cu. ft., said bottom having multiple upwardly opening article receiving compartments therein and a generally horizontal lip extending outwardly around the periphery at its upper end, a top section of unfoamed rigid transparent biaxially oriented polystyrene plastic having a thickness between about 5 to 30 mils, said top section having a generally fiat top wall, a pair of elongated planar sidewalls and a pair of planar end walls, each pair depending angularly outwardly from and integrally connected to the periphery of the top wall terminating in a generally laterally outwardly extending lip, a portion of the lip of the top section which extends along one of said sidewalls being hingedly connected along its full extent to the adjacent lip portion of said bottom section by means of an adhesive to permit opening the package by pivoting the top section with respect to the bottom section along the hinged connection and locking means comprising spot sealed portions for temporarily locking the opposite sidewall lip portion of the top section to the adjacent lip portion of the bottom section.

8. The package of claim 7 wherein the lip portion of the top section which is hingedly connected to the bottom section has an inwardly curled extension, the surface of which is sealed to the adjacent lip portion of the bottom section.

References Cited UNITED STATES PATENTS 3,258,187 6/ 1966 Greatman 2292.5 3,346,171 10/1967 Baker 22925 X 2,770,406 11/ 1956 Lane.

2,971,685 2/1961 Treida 2292.5 2,974,842 3/1961 Reifers 229----2.5 3,131,846 5/1964 Whitetord 22929 X 3,424,363 1/1969 Donovan 22929 X DAVIS T. MOORHEAD, Primary Examiner U.S. Cl. X.R. 2292.5 

